1. Tecnical Field
The present invention relates to a method for storing data obtained by digitizing content that is a work such as a movie, onto a large-capacity medium such as a digital optical disc, and enabling the data to be completely acquired only in a specific terminal. In particular, the present invention relates to a technique for transforming content data for copyright protection, and a technique for reproducing content data that is recorded on a large-capacity medium and has been encrypted and transformed for copyright protection.
2. Background Art
Systems in which content that is a work such as a movie is digitized, and stored and distributed on a medium have become widespread. In such a system, the content is recorded on the medium in an encrypted form, in order to prevent unauthorized use of the content. A reproducing device reads the encrypted content from the medium, decrypts the encrypted content, and reproduces the decrypted content.
Furthermore, a technique for preventing unauthorized copying of the content which has undergone the decryption in the reproducing device is disclosed in patent document 1. According to this technique, a digital watermark is embedded in the content generated as a result of decrypting the encrypted content. In so doing, unauthorized copying of the generated content can be suppressed. Even if the content is unauthorizedly copied, the device which copied the content unauthorizedly can be specified.
Patent document 1: Japanese Patent Application Publication No. 2000-312291
Patent document 2: Japanese Patent Application Publication No. 2000-100069
According to the above technique, however, there is a possibility that, during transfer from a decryption circuit to a digital watermark superimposing circuit, plaintext content before embedding a digital watermark may be extracted and used unauthorizedly. In view of this, the present invention aims to provide a data generating device, a data processing device, a recording medium, a data recording method, a data processing method, a data recording program, a data processing program, and an integrated circuit that can prevent unauthorized extraction of content between decryption processing and digital watermark embedment processing.